msem-instigator

Drown deals 2 damage to target creature. That creature can't block this turn.

Flash
When Devious Naiad enters, exchange control of it and target creature until end of turn. Untap that creature. It gains haste until end of turn.

Damage dealt by Deepwater Stinger can't be prevented.

Whenever Deceitful Soul becomes blocked by one or more creatures, it gets +2/+0 until end of turn.

Primal {R} (During your turn, you may cast this spell for {R} instead of playing a land.)
When Deadeye Drowner enters, it deals 2 damage to any target.

Up to two target creatures can't block this turn.
Draw a card.

Whenever Current Shaper perseveres, it deals 1 damage to each opponent. (A creature perseveres when it survives damage.)

{1}{R}: Crashcaller Nereid gets +1/+0 and gains trample until end of turn.

Whenever you cast a white spell, creatures you control get +1/+0 until end of turn.
Whenever you cast a blue spell, draw a card, then discard a card.

Creatures your opponents control have haste.

At the beginning of your upkeep, each player sacrifices a nonbasic land.

Sacrifice Voice of Ambition: Target creature gets +2/+1 until end of turn.

Starting with you, each player may sacrifice a creature. Each player that doesn't loses life equal to the total power of creatures sacrificed this way.

Deathtouch
Heretic (Whenever you cast a spell that doesn't share a color with this creature, it gets +1/+1 until end of turn.)

Primal {1}{G}{G} (During your turn, you may cast this spell for {1}{G}{G} instead of playing a land.)
When Swampedge Sentinel dies, return another creature card from your graveyard to your hand.

Whenever you cast a spell that doesn't share a color with Stinging Hunter, each opponent loses 1 life.

Target creature gets +2/+2 and gains lifelink until end of turn. Whenever that creature perseveres this turn, target opponent loses 2 life. (A creature perseveres when it survives damage.)

Creatures with power less than Skull-Crowned Chief's power can't block.

Destroy target token.

Whenever you gain life, target opponent loses that much life.

Primal {1}{W}{W} (During your turn, you may cast this spell for {1}{W}{W} instead of playing a land.)
Return target creature card from your graveyard to the battlefield.

As an additional cost to cast this spell, sacrifice a creature.
Look at the top X cards of your library, where X is the sacrificed creature's power. Put one of those cards into your hand and the rest into your graveyard.

Exile target creature you don't control. Its controller may search their library for a creature card with a different name, reveal it, put it into their hand, then shuffle.

{1}, Discard a card: Painted Watcher gets +1/+1 and becomes the color of your choice until end of turn.

Heretic (Whenever you cast a spell that doesn't share a color with this creature, it gets +1/+1 until end of turn.)
{1}{G}: Nightshade Slayer gets +2/+2 until end of turn. Activate only once each turn.